118. Pascal's Triangle

Given an integer numRows, return the first numRows of Pascal’s triangle.

动态规划,直接按照杨辉三角形的定义计算。

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class Solution {
public List<List<Integer>> generate(int numRows) {
ArrayList<List<Integer>> ans = new ArrayList<List<Integer>>(numRows);

for (int i = 0; i < numRows ; i++){
List<Integer> arr = new ArrayList<Integer>(i+1);

for (int j = 0; j <= i; j++){
if ( j == 0 || j == i ){
arr.add(1);
}
else{
arr.add(ans.get(i-1).get(j-1)+ans.get(i-1).get(j));
}
}
ans.add(arr);
}
return ans;
}
}

Author

Xander

Posted on

2022-04-06

Updated on

2022-04-20

Licensed under

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